Canopy lights are commonly used in outdoor service areas of fuel stations and convenience stores. Lighted canopies provide shelter, visibility, and security for consumers, as well as inviting storefronts that increase consumer traffic for businesses.
As applied to canopy lighting systems, digital lighting technologies such as light-emitting diodes (LEDs) offer significant advantages over legacy light sources such as incandescent, high-intensity discharge (HID), and fluorescent lamps. These advantages include, but are not limited to, better lighting quality, longer operating life, and lower energy consumption. Consequently, LED-based lamps increasingly are being used not only in original product designs, but also in products designed to replace legacy light sources in conventional lighting applications such as canopy systems. However, a number of design challenges and costs are associated with replacing traditional lamps with LED illumination devices. These design challenges include manufacturing cost control, installation ease, and thermal management.
Supplying power to LEDs is a key factor in quantifying the total cost of both retrofitting and operating a canopy lighting solution. While many approaches to driving LEDs are known in the art, the complex designs of current LED-based linear illumination devices often suffer from high material and component costs. LEDs are low-voltage light sources, requiring a constant DC voltage or current to operate optimally. More specifically, LEDs require power adapters to convert AC power drawn from a main supply to the proper DC voltage, and to regulate the current flowing through during operation to protect the LEDs from line-voltage fluctuations. To convert and regulate voltage and current, LED devices are commonly supplemented with an individual power adapter connecting to an AC electric power source. Such devices are usually compact enough to fit inside a junction box. However, the requirement to employ multiple converters and regulators with each LED-based lighting device results in higher total cost for system components.
Replacement of legacy lighting solutions may be complicated by the need to adapt LED-based devices to meet legacy form standards. For example, in a commercial lighting system retrofit, disposal of a replaced light's housing in a canopy structure often is impractical. Consequently, retrofit canopy light systems often are designed to adapt to legacy housing, both functionally and aesthetically. Also, legacy wiring used for delivery of electrical service is often reused in current retrofit solutions. The distribution wire carrying voltages of 110V or 220V from the main power supply to the plurality of converting devices must be protected against electric shock for safe use. Because of such safety concerns, a design that uses high-voltage distribution wire may be less desirable than a design that employs low-voltage DC distribution wire. However, the difficulty of quickly and safely installing new wiring without having to replace or cut pathways in existing structures, such as sheetrock or metal siding, leads current designers to instead reuse legacy wiring.
Another challenge inherent to operating LEDs is heat. Thermal management describes a system's ability to draw heat away from the LED, either passively or actively. LEDs suffer damage and decreased performance when operating in high-heat environments. Moreover, when operating in a confined environment, the heat generated by an LED and its attending circuitry itself can cause damage to the LED. Heat sinks are well known in the art and have been effectively used to provide cooling capacity, thus maintaining an LED-based light bulb within a desirable operating temperature. However, heat sinks can sometimes negatively impact the light distribution properties of the light fixture, resulting in non-uniform distribution of light about the fixture. Heat sink designs also may add to the weight of an illumination device, thereby complicating installation, and also may limit available space for other components needed for delivering light.
The lighting industry is experiencing advancements in LED applications, some of which may be pertinent to improving the design of linear illumination devices.
U.S. Pat. No. 5,997,158 to Fischer et al. discloses a retrofit luminaire assembly for mounting to an existing canopy fixture. The assembly includes a planar panel with electrical control elements mounted to a top surface of the panel and a light-emitting lamp mounted to a bottom surface of the panel. However, reliance on oppositely directed pivot members to mechanically support the planar panel when installed limits the size of canopy fixture housings to which the retrofit may be applied. Also, the depth of the electrical control elements presumes recessed mounting within an existing canopy fixture, thereby precluding low-profile flush-mounting applications.
U.S. Pat. No. 8,251,552 to Rooms et al. discloses an LED-based canopy luminaire designed for installation in a pre-existing fixture housing such that retrofitting requires minimum user effort and time. The canopy luminaire comprises a light panel, an external mounting panel, a connector plate, a power control unit, and a driver plate. However, including an expensive on-board power control unit for conversion and conditioning of power sacrifices manufacturing cost for the sake of installation ease. Also, construction and assembly of the many separate components listed above adds to design complexity and cost for the disclosed canopy luminaire.
U.S. Patent Application Publication No. 2012/0051048 by Smit et al. discloses a kit for retrofitting a non-LED canopy or other light fixture for use with LED lamps. The retrofit kit comprises a plurality of LED lamp units configured to attach to a cover replacement unit. However, similar to the Rooms disclosure, each of the LED lamp units is in electrical communication with a respective one of many on-board power supply units. Addition of power supply units not only add manufacturing cost to the retrofit kit, but also limits installation ease by requiring space for a power supply unit to extend through a canopy and into a legacy fixture (as in the Fischer disclosure).
Accordingly, a need exists for a low-profile, LED-based canopy light system that is less expensive to manufacture and assemble, easier and safer to install as a retrofit, and efficient at heat dissipation.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.